163 lines
4.4 KiB
C
163 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BLK_STAT_H
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#define BLK_STAT_H
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/ktime.h>
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#include <linux/rcupdate.h>
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#include <linux/timer.h>
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/**
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* struct blk_stat_callback - Block statistics callback.
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*
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* A &struct blk_stat_callback is associated with a &struct request_queue. While
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* @timer is active, that queue's request completion latencies are sorted into
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* buckets by @bucket_fn and added to a per-cpu buffer, @cpu_stat. When the
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* timer fires, @cpu_stat is flushed to @stat and @timer_fn is invoked.
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*/
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struct blk_stat_callback {
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/*
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* @list: RCU list of callbacks for a &struct request_queue.
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*/
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struct list_head list;
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/**
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* @timer: Timer for the next callback invocation.
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*/
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struct timer_list timer;
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/**
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* @cpu_stat: Per-cpu statistics buckets.
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*/
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struct blk_rq_stat __percpu *cpu_stat;
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/**
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* @bucket_fn: Given a request, returns which statistics bucket it
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* should be accounted under. Return -1 for no bucket for this
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* request.
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*/
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int (*bucket_fn)(const struct request *);
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/**
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* @buckets: Number of statistics buckets.
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*/
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unsigned int buckets;
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/**
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* @stat: Array of statistics buckets.
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*/
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struct blk_rq_stat *stat;
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/**
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* @fn: Callback function.
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*/
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void (*timer_fn)(struct blk_stat_callback *);
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/**
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* @data: Private pointer for the user.
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*/
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void *data;
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struct rcu_head rcu;
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};
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struct blk_queue_stats *blk_alloc_queue_stats(void);
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void blk_free_queue_stats(struct blk_queue_stats *);
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void blk_stat_add(struct request *rq, u64 now);
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/* record time/size info in request but not add a callback */
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void blk_stat_enable_accounting(struct request_queue *q);
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/**
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* blk_stat_alloc_callback() - Allocate a block statistics callback.
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* @timer_fn: Timer callback function.
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* @bucket_fn: Bucket callback function.
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* @buckets: Number of statistics buckets.
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* @data: Value for the @data field of the &struct blk_stat_callback.
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*
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* See &struct blk_stat_callback for details on the callback functions.
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*
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* Return: &struct blk_stat_callback on success or NULL on ENOMEM.
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*/
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struct blk_stat_callback *
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blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *),
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int (*bucket_fn)(const struct request *),
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unsigned int buckets, void *data);
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/**
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* blk_stat_add_callback() - Add a block statistics callback to be run on a
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* request queue.
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* @q: The request queue.
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* @cb: The callback.
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*
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* Note that a single &struct blk_stat_callback can only be added to a single
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* &struct request_queue.
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*/
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void blk_stat_add_callback(struct request_queue *q,
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struct blk_stat_callback *cb);
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/**
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* blk_stat_remove_callback() - Remove a block statistics callback from a
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* request queue.
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* @q: The request queue.
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* @cb: The callback.
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*
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* When this returns, the callback is not running on any CPUs and will not be
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* called again unless readded.
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*/
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void blk_stat_remove_callback(struct request_queue *q,
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struct blk_stat_callback *cb);
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/**
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* blk_stat_free_callback() - Free a block statistics callback.
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* @cb: The callback.
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*
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* @cb may be NULL, in which case this does nothing. If it is not NULL, @cb must
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* not be associated with a request queue. I.e., if it was previously added with
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* blk_stat_add_callback(), it must also have been removed since then with
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* blk_stat_remove_callback().
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*/
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void blk_stat_free_callback(struct blk_stat_callback *cb);
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/**
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* blk_stat_is_active() - Check if a block statistics callback is currently
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* gathering statistics.
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* @cb: The callback.
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*/
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static inline bool blk_stat_is_active(struct blk_stat_callback *cb)
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{
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return timer_pending(&cb->timer);
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}
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/**
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* blk_stat_activate_nsecs() - Gather block statistics during a time window in
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* nanoseconds.
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* @cb: The callback.
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* @nsecs: Number of nanoseconds to gather statistics for.
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*
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* The timer callback will be called when the window expires.
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*/
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static inline void blk_stat_activate_nsecs(struct blk_stat_callback *cb,
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u64 nsecs)
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{
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mod_timer(&cb->timer, jiffies + nsecs_to_jiffies(nsecs));
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}
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/**
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* blk_stat_activate_msecs() - Gather block statistics during a time window in
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* milliseconds.
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* @cb: The callback.
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* @msecs: Number of milliseconds to gather statistics for.
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*
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* The timer callback will be called when the window expires.
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*/
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static inline void blk_stat_activate_msecs(struct blk_stat_callback *cb,
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unsigned int msecs)
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{
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mod_timer(&cb->timer, jiffies + msecs_to_jiffies(msecs));
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}
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#endif
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